BETHESDA, Md. (WUSA) -- Montgomery Police are investigating an alleged attack which occurred on the popular Capital Crescent Trail at approximately 7 p.m. Sunday. Police say it may have been a sexual assault.

A woman says she was jogging and had stopped to let deer cross the trail between MacArthur Boulevard and Massachusetts Avenue when her attacker struck her on her head. She was knocked unconscious.

Police say she when regained consciousness she was off the trail in the woods. She walked back to the trail and yelled for help. A jogger heard her and helped her to Brooke Way Drive where they asked a homeowner to call police.

The woman is now in the hospital in in serious but stable condition.

According to police, she has been able to speak to detectives. Police say she described her attacker as a white male in his 20's who was wearing dark clothing.

There's been several other attacks on this trail in recent months, including three assaults and attempted robberies in the Wisconsin Avenue tunnel. But police say most of those crimes were committed by teenagers. They think what happened here is something entirely different.

Anyone with information about Sunday's crime is asked to call police at 240-773-5070 or Crime Solvers of Montgomery County at 1-866-411-TIPS (8477).